import math
x1,y1,x2,y2=map(float,input().split())
xx = (x2-x1)**2
yy = (y2-y1)**2
print(math.sqrt(xx + yy)) import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 xx = (x2-x1)**2 xx (x2-x1)**2 x2-x1 x2 x1 2 yy = (y2-y1)**2 yy (y2-y1)**2 y2-y1 y2 y1 2 print(math.sqrt(xx + yy)) print math.sqrt(xx + yy) math.sqrt math sqrt xx + yy xx yy yy = (y2-y1)**2 (y2-y1)**2 yy x2,y2=map(float,input().split()) map(float,input().split()) x2 xx = (x2-x1)**2 (x2-x1)**2 xx y2=map(float,input().split()) map(float,input().split()) y2 y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1
import math
x1,y1,x2,y2=map(float,input().split())
xx = (x2-x1)**2
yy = (y2-y1)**2
print(math.sqrt(xx + yy))